North Korea's Foreign Minister Ri Yong Ho on Monday accused US President Donald Trump of declaring war on his country by tweeting over the weekend that North Korea "won't be around much longer."

"Last weekend Trump claimed that our leadership wouldn't be around much longer and declared a war on our country," Ri said, according to an official translation of his remarks to reporters in New York.

"Since the United States declared war on our country, we will have every right to make all self-defensive counter measures, including the right to shoot down the United States strategic bombers at any time even when they are not yet inside the aerospace border of our country," Ri said.

White House press secretary Sarah Sanders said Monday that the US has not declared war on North Korea, adding, "Frankly, the suggestion of that is absurd."

Sanders said it is "never appropriate" to shoot down another nation's aircraft in international waters and the administration plans to continue to protect the area.

Earlier on Monday, State Department spokesperson Katina Adams told CNN the US seeks a "peaceful denuclearization of the Korean Peninsula."

But the US military "will take all options to make sure that we safeguard our allies and our partners and our homeland so if North Korea does not stop their provocative actions we'll make sure we provide options to the President to deal with North Korea," according to Col. Rob Manning, a Pentagon spokesman.

Asked about Ri's charge that Trump's comments were a declaration of war, Manning, said: "Our job as the Department of Defense is as you know is to make sure that the President is provided military options, we'll continue to do that, and we have a deep arsenal of military options to provide the President so then he can decide how he wants to deal with North Korea and the regime."

"We are postured and we are ready to fight tonight," he added.

The US Navy will also continue to maintain its presence near the Korean peninsula despite the latest round of harsh rhetoric and threats of a military strike from Pyongyang.